Selective bromination of perylene diimides and derivatives thereof under mild conditions

ABSTRACT

The present invention is directed to novel process for the preparation of regioselective perylenediimides derivatives, specifically mono and dibrominated derivatives.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application of PCT International Application No. PCT/IL2008/000621, International Filing Date May 6, 2008, which claims the benefit of Provisional Application Ser. No. 60/924,327, filed May 9, 2007 which is incorporated in its entirety by reference herein.

FIELD OF THE INVENTION

The present invention is directed to novel processes for the regioselective preparation of perylenediimides derivatives, specifically mono and dibrominated derivatives.

BACKGROUND OF THE INVENTION

Perylene-diimides (PDIs) are outstanding versatile organic chromophores. They demonstrate exceptional thermal and photochemical stability, strongly absorb visible light, and show high fluorescence quantum yields. PDIs have been utilized as industrial dyes, electronic materials, sensors, photovoltaics, and building blocks for light-harvesting and artificial photosynthetic systems. Importantly, photophysical and redox properties of PDIs can be conveniently modified through substitution in the aromatic core at the positions 1, 6, 7, and 12 (bay region). Substitutions at bay positions and expansion of the PDI core are usually carried out starting from the halogenated derivatives, particularly brominated PDIs. These are almost exclusively synthesized through bromination of perylene dianhydride (PDA) in concentrated H₂SO₄ upon heating, followed by imidation with amines. Usually this bromination procedure affords a mixture of di-, tri- and tetrabrominated PDIs. The dibromoperylene diimides contain 1,7 (major) and 1,6 (minor) regioisomers. Recently, purification of 1,7 regioisomer by repetitive recrystallization has been reported. Among the brominated perylene-diimides, 1,7-dibrominated PDIs are the most widely used as starting materials for a broad variety of PDI derivatives.

There is a need in the art to develop synthetic methods for the synthesis of regioselective PDIs compounds, that can provide highly pure products in high yield.

SUMMARY OF THE INVENTION

In one embodiment this invention provides a process for the preparation of dibrominated perylene diimide compound represented by the structures of formula 1,6-3 and 1,7-3;

-   -   wherein R₁ and R₂ are the same or different comprising         substituted or unsubstituted linear or branched alkyl group,         substituted or unsubstituted saturated carbocyclic or         heterocyclic ring or aryl;     -   comprising the steps of         -   a) brominating compound of formula 1

-   -   wherein R₁ and R₂ are as defined above;     -   in the presence of bromine and a chlorinated solvent at reflux         for a period of time sufficient to obtain a mixture comprising         compounds of formula 1,6-3 and 1,7-3; and     -   b) separating between 1,6-3 and 1,7-3 regioisomer compounds by         recrystallizing compound of formula 1,7-3 yielding crystalline         pure perylenediimide of formula 1,7-3, thereby separating         between said regioisomer compounds.

In one embodiment, this invention provides a process for the preparation of dibrominated perylene-diimide and monobrominated perylene-diimide compounds represented by the structures of formula 2, 1,6-3 and 1,7-3;

-   -   wherein R₁ and R₂ are the same or different comprising         substituted or unsubstituted linear or branched alkyl group,         substituted or unsubstituted saturated carbocyclic or         heterocyclic ring or aryl;     -   comprising the steps of         -   a) brominating compound of formula 1

-   -   wherein R₁ and R₂ are as defined above;     -   in the presence of bromine and a chlorinated solvent at a         temperature ranging between about 15-30° C. for a period of time         sufficient to obtain a mixture comprising compound of formula 2,         1,6-3 and 1,7-3;         -   b) isolating compound of formula 2 by chromatography; and         -   c) separating between 1,6-3 and 1,7-3 regioisomer compounds             by recrystallizing compound of formula 1,7-3 yielding             crystalline pure perylene-diimide of formula 1,7-3, thereby             separating between said two regioisomer compounds.

In one embodiment, this invention provides a perylene-diimide compound represented by the structure of formula 4:

-   -   wherein     -   R₁ and R₂ are the same or different comprising substituted or         unsubstituted linear or branched alkyl group, substituted or         unsubstituted saturated carbocyclic or heterocyclic ring or         aryl;     -   R₃ is a saturated or unsaturated heterocyclic ring, saturated or         unsaturated carbocyclic ring, alkyl, alkylene, alkynyl,         acetylene, diphenylacetylene, phenylacetylene,         ethynyl-phenyl-2,2′;6′ 2″-terpyridine, 1,4-diethynylbenzene or         Z-perylene;         -   Z is 1,4 diethynylbenzene, phenyl, acetylene, aryl,             cycloalkyl, heterocycle, olefin, azo, amide, C═N,N═C,             carbonyl, 1,4 divinylbenzene, piperidine,             5,5′-Diethynyl-2,2′-Bipyridine, dialcohol or dithiol; and             optionally a metal or a metal ion is coordinated to said             perylene diimide compound forming a metal complex with said             compound.

In another embodiment, this invention provides a compound represented by the structure of compound 5:

In another embodiment, this invention provides a compound represented by the structure of compound 6:

In another embodiment, this invention provides a compound represented by the structure of compound 7:

In another embodiment, this invention provides a compound represented by the to structure of compound 8:

In another embodiment, this invention provides a compound represented by the structure of compound 9:

In another embodiment, this invention provides a compound represented by the structure of compound 10:

In another embodiment, this invention provides a compound represented by the structure of compound 11:

In another embodiment, this invention provides a compound represented by the structure of compound 12:

In another embodiment, this invention provides a compound represented by the structure of compound 13:

In another embodiment, this invention provides a compound represented by the structure of compound 14:

In another embodiment, this invention provides a compound represented by the structure of compound 15:

In another embodiment, this invention provides a compound represented by the structure of compound 16:

In another embodiment, this invention provides a compound represented by the structure of compound 17:

In one embodiment, this invention provides a compound represented by the structure of compound 18:

wherein a metal or a metal ion is optionally coordinated with the terpyridine group forming a metal complex.

In one embodiment, this invention provides a compound represented by the structure of compound 19:

wherein a metal or metal ion is optionally coordinated with the bipyridine group forming a metal complex.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the appended drawings in which:

FIG. 1 is a synthetic scheme for the preparation of compounds of formula 2a, 2b, 2c, 3a and 3b providing the reagents and conditions for the different regioisomers: (a) 2a and 3a: Br₂, CH₂Cl₂, 22-24° C., 2 days, 26% of 2a and 57% of mixture of regioisomers 1,7-3a and 1,6-3a (5:1); 2b and 3b: Br₂, CH₂Cl₂, 22-24° C., 4 days, 25% of 2b and 50% of mixture of 1,7-3b and 1,6-3b (5:1); (b): 3a: Br₂, CH₂Cl₂, reflux, 24 hr, 85% of mixture of 1,7-3a and 1,6-3a (3:1); 3b: Br₂, CH₂Cl₂, reflux, 2 days, 89% of mixture of 1,7-3b and 1,6-3b (3:1); 3c: Br₂, CH₂Cl₂, reflux, 4 days, 85% of mixture of 1,7-3c and 1,6-3c (3:1).

FIG. 2 depicts ¹H NMR spectra of a regioisomeric mixture of 1,7-3a and 1,6-3a before recrystallization (FIG. 2A); ¹H NMR spectra of 1,7-3a obtained after three repetitive recrystallizations of the regioisomeric mixture, (FIG. 2B); and ¹H NMR spectra of the mother liquor obtained in the first recrystallization (1,6-3a is a dominant species) (FIG. 2C).

FIG. 3 depicts ¹³C {¹H} NMR spectra of carbonyl peaks of regioisomeric mixture of 1,7-3a and 1,6-3a before recrystallization (FIG. 3A); ¹³C {¹H} NMR spectra of 1,7-3a obtained after three repetitive recrystallizations of the regioisomeric mixture (FIG. 3B); and ¹³C {¹H} NMR spectra of the mother liquor obtained in the first recrystallization (contains mostly 1,6-3a) (FIG. 3C).

FIG. 4 depicts ¹H NMR spectra of a regioisomeric mixture of 1,7-3b and 1,6-3b before recrystallization, (FIG. 4A); and ¹H NMR spectra of pure 1,7-3b, obtained after three repetitive recrystallizations of the regioisomeric mixture (FIG. 4B).

FIG. 5 depicts ORTEP drawing of structure of 1,7-3b (left, 50% probability, hydrogens are omitted for clarity) and view along the N-N axis showing twisted perylene backbone (right, 50% probability, alkyl groups at imide nitrogens and all hydrogens are omitted for clarity). There is a minor disorder in one of the ethylpropyl groups. Selected bond lengths (Å): Br1-C1, 1.905 (4); C1-C2, 1.402 (5); C2-C3, 1.375 (6); C3-C13, 1.486 (5); C13-N1, 1.395 (6); C13-O2, 1.225 (6); C3-C20, 1.406 (6); C20-C21, 1.423 (5); C21-C22, 1.434 (5); C22-C1, 1.403 (5); C22-C34, 1.468 (5).

FIG. 6 is a synthetic scheme for the preparation of compounds of formula 5, 6, 7 and 8 providing the reagents and conditions for the different regioisomers (a) piperidine, 60° C., N2, 5 h, 96% of 5 and 96% of 6; (b) Pd(PPh₃)₄ (10 mol %), CuI (5 mol %), trimethylsilyl acetylene, diisopropylamine, rt, 96% of 7 and 97% of 8.

FIG. 7A-B depicts computed structures for rotational isomers and the transition states for imide group rotation. Hydrogens (except for NCHR₂) are omitted for clarity.

FIG. 8 depicts computed structures for rotational isomers and the transition states for core twist in monobromo-PDI (FIG. 8A); and core twist in dibromo-PDI. (FIG. 8B).

FIG. 9 depicts ¹H NMR spectra of compound of formula 11.

FIG. 10 depicts ¹H NMR spectra of compound of formula 12.

FIG. 11 depicts ¹H NMR spectra of compound of formula 13.

FIG. 12 depicts ¹H NMR spectra of compound of formula 14.

FIG. 13. depicts ¹H NMR spectra of compound of formula 16.

FIG. 14. depicts ¹H NMR spectra of compound of formula 17.

FIG. 15. depicts ¹H NMR spectra of compound of formula 18.

FIG. 16 depicts ¹H NMR spectra of compound of formula 19.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

This invention provides a perylene-diimide bromination methodology that employs mild conditions (organic solvent, room temperature) resulting in facile formation of mono perylene-diimides and dibrominated perylene-diimides. The selectivity of the reaction toward exclusive dibromination can be controlled through variation of the reaction conditions. Computational studies on the imide group rotation and PDI aromatic core provide insight into the inherent dynamics of PDI molecules.

In one embodiment, a dibrominated perylene-diimide compound of this invention refers to 1,7-dibromo-N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (1,7-3a). In another embodiment, dibrominated perylene-diimide compound of this invention refers to 1,7-dibromo-N,N′-bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (1,7-3b). In another embodiment, dibrominated perylene-diimide compound of this invention refers to 1,7-dibromo-N,N′-bis(cyclohexyl)perylene-3,4:9,10-tetracarboxylic diimide (1,7-3c). In another embodiment, dibrominated perylene-diimide compound of this invention refers to 1,6-dibromo-N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (1,6-3a). In another embodiment, dibrominated perylene-diimide compound of this invention refers to 1,6-dibromo-N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (1,6-3b). In another embodiment, dibrominated perylene-diimide compound of this invention refers to 1,6-dibromo-N,N′-Bis(cyclohexyl)perylene-3,4:9,10-tetracarboxylic diimide (1,6-3c)

In another embodiment, monobrominated perylene-diimide compound of this invention refers to 1-bromo N,N′-bis(2,4-dimethylpent-3-yl) perylene-3,4:9,10-tetracarboxylic diimide (2a). In another embodiment, brominated perylene-diimide compound of this invention refers to 1-bromo N,N′-bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (2b).

Some embodiments of a synthetic procedure for some of the PDIs are provided below:

In one embodiment, the solubility of the compounds decreases 1a>1b>1c, reflecting the decrease of the imide substituent bulk and the increase of PDI aggregation propensity, which is controlled by π-π stacking. In another embodiment, bromination of 1a would be highly desirable since it is a starting point for further derivatization, which can lead to novel photonic materials.

In one embodiment, this invention provides, a process for the preparation of dibrominated perylene-diimide compound represented by the structures of formula 1,6-3 and 1,7-3;

-   -   wherein R₁ and R₂ are the same or different comprising         substituted or unsubstituted linear or branched alkyl group,         substituted or unsubstituted saturated carbocyclic or         heterocyclic ring or aryl;     -   comprising the steps of         -   a) brominating compound of formula 1

wherein R₁ and R₂ are as defined above;

-   -   in the presence of bromine and a chlorinated solvent at reflux         for a period of time sufficient to obtain a mixture comprising         compounds of formula 1,6-3 and 1,7-3; and     -   b) separating between 1,6-3 and 1,7-3 regioisomer compounds by         recrystallizing compound of formula 1,7-3 yielding crystalline         pure perylenediimide of formula 1,7-3, thereby separating         between said regioisomer compounds.

In one embodiment, this invention provides a process for the preparation of dibrominated perylene-diimide and monobrominated perylene-diimide compounds represented by the structures of formula 2, 1,6-3 and 1,7-3;

-   -   wherein R₁ and R₂ are the same or different comprising         substituted or unsubstituted linear or branched alkyl group,         substituted or unsubstituted saturated carbocyclic or         heterocyclic ring or aryl;     -   comprising the steps of         -   a) brominating compound of formula 1

-   -   wherein R₁ and R₂ are as defined above;     -   in the presence of bromine and a chlorinated solvent at a         temperature ranging between about 15-30° C. for a period of time         sufficient to obtain a mixture comprising compound of formula 2,         1,6-3 and 1,7-3;         -   b) isolating compound of formula 2 by chromatography; and         -   c) separating between 1,6-3 and 1,7-3 regioisomer compounds             by recrystallizing compound of formula 1,7-3 yielding             crystalline pure perylene-diimide of formula 1,7-3, thereby             separating between said two regioisomer compounds.

In one embodiment, the processes of this invention comprise a chlorinated solvent. In another embodiment, the chlorinated solvent is dichloromethane (DCM). In another embodiment, the chlorinated solvent is chloroform. In another embodiment, the chlorinated solvent is tetrachloromethane. In another embodiment, the chlorinated solvent is an aliphatic chlorinated solvent.

Some embodiments of the process for the preparation of perylene-diimides compounds of this invention are exemplified herein in Examples 1-15, which serve as guidance for one of skill in the art to practice this invention, which as will be appreciated, may comprise other variations of such processes and compounds, and be within the scope of this invention. According to this aspect, and as exemplified herein, mono-bromination of perylene-diimide compound of formula 1, was accomplished within a period of time of between 1-4 days. In one embodiment, mono-bromination of perylene-diimide compound of formula 1, was accomplished within a period of time of between 24-48 h. In one embodiment, mono-bromination of perylene-diimide compound of formula 1, was accomplished within a period of time of between 24-72 h. In another embodiment, bis-bromination of perylene-diimide compound of formula 1, was accomplished within a period of time of between 1-4 days. In one embodiment, bis-bromination of perylene-diimide compound of formula 1, was accomplished within a period of time of between 24-48 h. In one embodiment, bis-bromination of perylene-diimide compound of formula 1, was accomplished within a period of time of between 24-72 h.

In one embodiment, the processes of this invention provides separation between 1,6-dibromo-perylene-diimide regioisomers and 1,7-dibromo-perylene-diimide regioisomers of this invention. In another embodiment, the separation and/or isolation of 1,7-dibromo-perylene-diimide regioisomers are performed by recrystallization. In another embodiment, the recrystallization is from a mixture of dichloromethane/hexane (v/v, 1:1).

In some embodiments, 500 MHz ¹H NMR spectra of 3 showed the presence of 1,7-3 and 1,6-3 regioisomers (for example in 5:1 ratio respectively, FIG. 2), which could not be separated using column chromatography. The major 1,7-3 regioisomer can be purified by repetitive recrystallization from dichloromethane/hexane mixture (v/v, 1:1). The recrystallization process is monitored by 500 MHz ¹H NMR spectroscopy (FIG. 2). After successive recrystallizations, the regioisomer 1,7-3 is obtained as indicated by the ¹H (FIG. 2) and ¹³C NMR spectra (FIG. 3). In mother liquor, the isomer 1,6-3 is a major species to (FIGS. 2 and 3).

In one embodiment, the processes of this invention for the preparation of mono-brominated perylene-diimide is conducted at a temperature of between about 15-30° C., or in another embodiment, between about 22-24° C., or in another embodiment, between about 25-30° C., or in another embodiment, between about 18-24° C.

In one embodiment, the processes of this invention for the preparation of bis-brominated perylene-diimide is conducted at a temperature of between about 15-30° C., or in another embodiment, between about 22-24° C., or in another embodiment, between about 25-30° C., or in another embodiment, between about 18-24° C., or in another embodiment, between about 50-60° C., or in another embodiment, at a reflux temperature of the chlorinated solvent.

In one embodiment, high resolution ¹H and ¹³C NMR spectra of compound 1a (starting material in bromination reaction), suggested that two very similar isomers in 1:1 ratio are present. This phenomenon was addressed by computational studies (Example 19), revealing that the isomers are due to restricted rotation (kinetic barrier of ˜32 kcal/mol) of the bulky dimethylpentyl group around N—C bond, (FIG. 7) for the structures of the rotational isomers. Restricted rotation of bulky PDI imide substituents (2,5-di-tert-butylphenyls) leading to two isomers has been reported. All dimethylpentyl PDI derivatives described below contain two rotational isomers in 1:1 ratio. Clear observation of the signals for the two isomers in NMR spectra of dimethylpenthyl PDIs was possible only using 500 MHz NMR.

In one embodiment, the facility of the bromination reactions (as exemplified by the reaction times and temperatures) decreases in a row 1a>1b>1c. This trend supports the notion that the reactivity of PDIs depends on their aggregation (which also influences their solubility properties). Notably, while bromination of 1a is very facile at room temperature, compound 1c cannot be brominated at ambient temperatures.

In one embodiment, this invention provides a perylene-diimide compound represented by the structure of formula 4:

-   -   wherein     -   R₁ and R₂ are the same or different comprising substituted or         unsubstituted linear or branched alkyl group, substituted or         unsubstituted saturated carbocyclic or heterocyclic ring or         aryl;     -   R₃ is saturated or unsaturated heterocyclic ring, saturated or         unsaturated carbocyclic ring, alkyl, alkylene, alkynyl,         acetylene, diphenylacetylene,         ethynyl-phenyl-2,2′;6′2″-terpyridine, phenylacetylene,         1,4-diethynylbenzene or Z-perylene;         -   Z is 1,4 diethynylbenzene, phenyl, acetylene, aryl,             cycloalkyl, heterocycle, olefin, azo, amide, C═N, N═C,             carbonyl, 1,4 divinylbenzene, piperidine, dialcohol,             5,5′-Diethynyl-2,2′-bipyridine or dithiol; and     -   optionally a metal or a metal ion is coordinated to said         perylene diimide compound forming a metal complex with said         compound.

In one embodiment, the perylene-diimide compounds and the compounds used in the process of this invention comprise R₁ and R₂ substituents. In another embodiment, the R₁ and R₂ are the same or different comprising substituted or unsubstituted linear or branched alkyl, or substituted or unsubstituted saturated carbocyclic ring. In another embodiment, R₁ and R₂ comprise substituted or non substituted linear alkyl. In another embodiment, R₁ and R₂ comprise substituted or unsubstituted branched alkyl. In another embodiment, R₁ and R₂ comprise substituted or unsubstituted saturated carbocyclic ring. In another embodiment, R₁ and R₂ comprise substituted or unsubstituted aryl. In another embodiment, R₁ and R₂ are the same or different comprising dimethylpentyl, tertbutyl, ethylpropyl, linear alkyl (C₁-C₁₂), cyclohexane, or any combination thereof.

In one embodiment, the perylene-diimide compounds and the compounds used in the process of this invention comprise R₃ substituents. In another embodiment, R₃ is saturated or unsaturated heterocyclic ring. In another embodiment, R₃ is saturated or unsaturated carbocyclic ring. In another embodiment, R₃ is alkyl. In another embodiment, R₃ is alkylene. In another embodiment, R₃ is alkynyl. In another embodiment, R₃ acetylene. In another embodiment, R₃ is diphenylacetylene. In another embodiment, R₃ is phenylacetylene. In another embodiment R₃ is piperazine. In another embodiment R₃ is pyridine. In another embodiment R₃ is bipyridine. In another embodiment, R₃ is piperidine. In another embodiment R₃ is

In another embodiment R₃ is trimethylsilylethynyl

In another embodiment R₃ is ethynyl-trimethylsilylbenzene. In another embodiment R₃ is -ethynyl-phenyl-2,2′;6′2″-terpyridine. In another embodiment, R₃ is 1,4-diethynylbenzene. In another embodiment, R₃ is Z-perylene wherein Z is 1,4 diethynylbenzene, phenyl, acetylene, aryl, cycloalkyl, heterocycle, olefin, azo, amide, C═N, N═C, carbonyl, 1,4 divinylbenzene, piperidine, dialcohol, 5,5′-Diethynyl-2,2′-bipyridine, or dithiol.

An “alkyl” group refers, in one embodiment, to a saturated aliphatic hydrocarbon, including straight-chain, branched-chain and cyclic alkyl groups. In one embodiment, the alkyl group has 1-12 carbons. In another embodiment, the alkyl group has 1-7 carbons. In another embodiment, the alkyl group has 1-6 carbons. In another embodiment, Examples of alkyl groups are methyl, ethyl, propyl, isobutyl, butyl, pentyl or hexyl. In another embodiment, the alkyl group has 1-4 carbons. The alkyl group may be unsubstituted or substituted by one or more groups selected from halogen, hydroxy, alkoxy, carboxylic acid, aldehyde, carbonyl, amido, cyano, alkylamido, dialkylamido, nitro, amino, alkylamino, dialkylamino, carboxyl, thio and thioalkyl.

An “alkenyl” group refers, in another embodiment, to an unsaturated hydrocarbon, including straight chain, branched chain and cyclic groups having one or more double bonds. The alkenyl group may have one double bond, two double bonds, three double bonds, etc. In another embodiment, the alkenyl group has 2-12 carbons. In another embodiment, the alkenyl group has 2-6 carbons. In another embodiment, the alkenyl group has 2-4 carbons. In another embodiment the alkenyl group is ethenyl (—CH═CH₂) Examples of alkenyl groups are ethenyl, propenyl, butenyl, cyclohexenyl, etc. The alkenyl group may be unsubstituted or substituted by a halogen, hydroxy, alkoxy carbonyl, amido, alkylamido, dialkylamido, nitro, cyano, amino, alkylamino, dialkylamino, carboxyl, thio and/or thioalkyl.

An “alkynyl” group refers, in another embodiment, to an unsaturated hydrocarbon, including straight chain, branched chain and cyclic groups having one or more triple bonds. The alkynyl group may have one triple bond, two triple bonds, three triple bonds, etc. In another embodiment, the alkynyl group has 2-12 carbons. In another embodiment, the alkynyl group has 2-6 carbons. In another embodiment, the alkynyl group has 2-4 carbons. In another embodiment the alkynyl group is ethynyl. Examples of alkenyl groups are ethynyl, propynyl, butynyl, cyclohexynyl, etc. The alkynyl group may be unsubstituted or substituted by a halogen, hydroxy, alkoxy carbonyl, cyano, amido, alkylamido, dialkylamido, nitro, amino, alkylamino, dialkylamino, carboxyl, thio and/or thioalkyl.

In one embodiment, the term “halogen refers to in one embodiment to F, in another embodiment to Cl, in another embodiment to Br, in another embodiment to I.

A “carbocyclic ring” group refers, in one embodiment, to a saturated or non saturated hydrocarbon ring. In one embodiment, the carbocyclic ring group has 4-12 carbons. In another embodiment, the carbocyclic ring group has 4-8 carbons. In another embodiment, the carbocyclic ring comprise of 2-3 fused rings. In another embodiment, Examples of a carbocyclic ring are cyclohexane, cyclopentane, phenyl or 1-cyclopentene. The carbocyclic ring may be substituted by one or more groups selected from halogen, hydroxy, alkoxy, carboxylic acid, aldehyde, carbonyl, amido, cyano, alkylamido, dialkylamido, nitro, amino, alkylamino, dialkylamino, carboxyl, thio and thioalkyl.

A “heterocycle” group refers, in one embodiment, to a ring structure comprising in addition to carbon atoms, sulfur, oxygen, nitrogen or any combination thereof, as part of the ring. In another embodiment the heterocycle is a 3-12 membered ring. In another embodiment the heterocycle is a 6 membered ring. In another embodiment the heterocycle is a 5-7 membered ring. In another embodiment the heterocycle is a 4-8 membered ring. In another embodiment, the hetrocycle is terpyridine, piperazine, piperidine, pyridine, thiophen, furane, pyrrole, pyrrolidine, bipyridine or pyrazine. In another embodiment, the heterocycle group may be unsubstituted or substituted by a halogen, haloalkyl, hydroxyl, alkoxy, carbonyl, amido, alkylamido, dialkylamido, cyano, nitro, CO₂H, amino, alkylamino, dialkylamino, carboxyl, thio and/or thioalkyl. In another embodiment, the heterocycle ring may be fused to another saturated or unsaturated cycloalkyl or heterocyclic 3-8 membered ring. In another embodiment, the heterocyclic ring is a saturated ring. In another embodiment, the heterocyclic ring is an unsaturated ring.

In one embodiment, this invention provides a compound represented by the structure of compound 5:

In one embodiment, this invention provides a compound represented by the structure of compound 6:

In one embodiment, this invention provides a compound represented by the structure of compound 7:

In one embodiment, this invention provides a compound represented by the structure of compound 8:

In one embodiment, this invention provides a compound represented by the structure of compound 9:

In one embodiment, this invention provides a compound represented by the structure of compound 10:

In one embodiment, this invention provides a compound represented by the structure of compound 11:

In one embodiment, this invention provides a compound represented by the structure of compound 12:

In one embodiment, this invention provides a compound represented by the structure of compound 13:

In one embodiment, this invention provides a compound represented by the structure of compound 14:

In one embodiment, this invention provides a compound represented by the structure of compound 15:

In one embodiment, this invention provides a compound represented by the structure of compound 16:

In one embodiment, this invention provides a compound represented by the structure of compound 17:

In one embodiment, this invention provides a compound represented by the structure of compound 18:

wherein a metal or metal ion is optionally coordinated with the terpyridine group forming a metal complex.

In one embodiment, this invention provides a compound represented by the structure of compound 19:

wherein a metal or metal ion is optionally coordinated with the bipyridine group forming a metal complex.

In another embodiment, a metal is optionally coordinated to the compounds of this invention via a chelating group. In another embodiment, Z, R₁, R₂ and R₃ comprise independently a chelating group, wherein the chelating group is attached directly or indirectly to the perylene or imide. In another embodiment, the chelating group is attached via an ethenyl to bridge, phenyl bridge, or any combination thereof. In another embodiment, the chelating group forms a complex with a metal or metal ion. In another embodiment, the metal or metal ion comprises Pd, Pt, Fe, Cu, Ag, Rh, Ir, Ru or Os. In another embodiment the chelating agent comprises a diamine, a dicarboxylic acid, a pyridine, a bipyridine, a terpyridine, a diazo, a mercapto, a acetylacetone, a benzoylacetone, a salysilic acid, a carboxylic acid, an ethylene diamine tetraacetic acid (EDTA) moeity, or any combination thereof. In another embodiment, compounds (18) and (19) are exemplified compounds which possess a chelating group.

In one embodiment, the preparation of monobrominated PDIs (2a,b) is disclosed hereinabove and exemplified in Examples 1 and 2. Compounds of formula 2a and 2b they are used, in some embodiments for further functionalization at the bay position to give novel unsymmetrical derivatives. Some embodiments of a synthetic procedure for some of the PDIs are provided below:

In one embodiment, The nucleophilic substitution of mono bromoperylene diimide (2a,b) with piperidine afforded the corresponding monopiperidinyl-diimides 5 and 6. Sonogashira cross-coupling afforded ethynyl derivatives 7 and 8 (Examples 4-7).

In one embodiment, the compounds of this invention are incorporated in electroluminescent devices such as thin-film. In another embodiment, the compounds of this invention modify the light emitted in electroluminescent devices. In another embodiment, the compounds of this invention are incorporated in the electroluminescent layer or in the electron transmitting layer. In another embodiment, the light is emitted in the electroluminescent material layer in response to the injection and combination of holes in the layer. If a fluorescent material is added to the electroluminescent the color of the emitted light can be varied. In theory, if an electroluminescent host material and a fluorescent material could be found for blending which have exactly the same affinity for hole-electron recombination each material should emit light upon injection of holes and electrons in the luminescent zone. Choosing fluorescent materials capable of providing favored sites for light emission necessarily involves relating the properties of the fluorescent material to those of the host material. The host material can be viewed as a collector for injected holes and electrons with the fluorescent material providing the molecular sites for light emission.

The following examples are presented in order to more fully illustrate the preferred embodiments of the invention. They should in no way be construed, however, as limiting the broad scope of the invention.

EXAMPLES Materials and Methods

General Methods. Solvents and reagents were obtained from commercial sources and used as received. NMR spectra were recorded at room temperature on 500 MHz NMR spectrometer unless otherwise specified. CDCl₃ was used as an NMR solvent. The chemical shifts (δ) are reported in parts per million (ppm) from tetramethylsilane (TMS, 0.00 ppm). Proton spectra recorded in CDCl₃ were referenced to TMS. Carbon spectra recorded in CDCl₃ were referenced to the peak of CDCl₃ (77.0 ppm).

The solvents for spectroscopic studies were of spectroscopic grade and used as received. UV/vis spectra were measured on a Cary spectrometer. Steady-state fluorescence spectra were measured on a Cary Eclipse instrument and fluorescence quantum yields were determined using N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3, 4:9,10-tetracarboxylicdiimide (Φ=1) as reference for compounds 2a, 2b, 3a, 3b, 7 and 8 and N,N′-Dicyclohexyl-1,7-dipiperidinylperylene-3,4:9,10-tetracarboxylic diimide (Φ=0.2) as reference for compounds 5 and 6.

Electrochemical measurements were performed using a CHI electrochemical workstation. Methylene chloride containing 0.1M tetra-n-butylammonium hexafluorophosphate (TBAPF₆) was used as a solvent. Ferrocene/ferrocenium redox couple (Fc/Fc⁺, 0.475 V vs SCE in CH₂Cl₂) was used as an internal reference for all measurements. All electrochemical measurements were performed under dry nitrogen atmosphere. Electrospray Ionization (ESI) Mass-Spectrometry was performed using Micromass Platform instrument. Melting points for all compounds exceeded 300° C.

Example 1 Synthesis of 1-bromo N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (2a) and 1,7-dibromo-N,N′-Bis(2,4-dimethylpent-3-yl) perylene-3,4:9,10-tetracarboxylic diimide (1,7-3a)

Bromination of N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (1a). A mixture of 1a (1 g, 1.7 mmol) and bromine (18.66 g, 0.116 mol) in 60 ml of dichloromethane was stirred at 22-24° C. in a closed round bottom flask for 2 days. The excess of bromine was removed by air bubbling and the solvent was removed under vacuum. The crude product was purified by silica gel column chromatography with chloroform as an eluent. The first band was collected to afford dibromo perylene diimide (mixture of 1,7-3a and 1,6-3a in 5:1 ratio) as an orange solid (330 mg, 26%). The second band afforded 1-bromo N,N′-Bis(2,4-dimethyl pent-3-yl)perylene diimide 2a (650 mg, 57%) as an orange solid. The third to band gave the unreacted perylene diimide 1(150 mg, 15%). The regioisomers, 1,7-3a and 1,6-3a, could not be separated by column chromatography.

Regioisomerically pure 1,7-dibromo perylene diimide (1,7-3a) was obtained by repetitive crystallization. The mixture (330 mg) of 1,7-3a and 1,6-3a (5:1) was crystallized from 50 ml of CH₂Cl₂:Hexane (v/v, 1:1) mixture at room temperature for 5 days. The crystallization was repeated at the same conditions for two more times to yield 180 mg (55%) of pure 1,7-3a as an orange solid.

1-bromo N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (2a) ¹H NMR: δ 9.8 (m, 2H), 8.96 (s, 1H), 8.93 (s, 1H), 8.6-8.75 (m, 10H), 4.75 (m, 4H), 2.72 (m, 8H), 1.13 (d, 12H, J=6.5 Hz), 1.12 (d, 12H, J=7.0 Hz), 0.95 (d, 12H, J=7.0 Hz), 0.94 (d, 12H, J=6.5 Hz). ¹³C {¹H} NMR: δ 165.26, 164.94, 164.89, 164.13, 164.09, 163.81, 163.77, 162.93, 139.58, 138.94, 133.97, 133.94, 133.91, 133.88, 133.63, 133.60, 133.58, 133.57, 133.53, 131.61, 131.09, 130.90, 130.38, 128.92, 128.91, 128.72, 128.71, 128.11, 128.09, 127.04, 124.03, 124.02, 123.86, 123.84, 123.78, 123.75, 123.56, 123.54, 123.41, 123.39, 123.25, 123.23, 123.01, 123.00, 122.98, 122.96, 122.94, 122.66, 122.64, 120.97, 120.95, 120.92, 65.41, 65.35, 65.20, 65.19, 29.11, 29.10, 29.06, 29.01, 21.80, 21.72, 20.57, 20.51, 20.50. MS 664.50 [M⁺] (calcd 664.19). UV/vis (CHCl₃): λ_(max)/nm (ε/M⁻¹ cm⁻¹)=524 (74 669), 488 (48 630), 458 (18 465). Fluorescence (CHCl₃): λ_(max)=538 nm, fluorescence quantum yield Φ_(f)=0.92. Anal. Calcd. for C₃₈H₃₇BrN₂O₄: C, 68.57; H, 5.60; N, 4.21. Found: C, 68.43; H, 5.61; N, 4.33.

1,7-dibromo-N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (1,7-3a). ¹H NMR: δ 9.52 (d, 1H, J=8.0 Hz), 9.50 (d, 1H, J=8.0 Hz), 8.95 (s, 1H), 8.92 (s, 1H), 8.73 (d, 1H, J=8.0 Hz), 8.68 (d, 1H, J=8.0 Hz), 4.75 (two triplets merged t, 2H, J=8.5 Hz), 2.72 (m, 4H), 1.12 (d, 12H, J=7.0 Hz), 0.94 (d, 12H, J=7.0 Hz). ¹³C {¹H} NMR: δ 164.66, 164.17, 163.53, 163.00, 138.53, 137.90, 132.90, 132.88, 132.84, 132.77, 132.71, 130.57, 129.86, 129.25, 128.45, 127.14, 123.63, 123.24, 123.22, 123.02, 123.00, 122.64, 122.62, 120.76, 65.44, 65.36, 29.05, 29.02, 21.72, 20.49. MS 742.38 [M⁺] (calcd 742.10). UV/vis (CHCl₃): λ_(max)/nm (ε/M⁻¹ cm⁻¹)=526 (49 825), 490 (33 702), 463 (13 458). Fluorescence (CHCl₃): λ_(max)=545 nm, fluorescence quantum yield Φ_(f)=0.82. Anal. Calcd. for C₃₈H₃₆Br₂N₂O₄: C, 61.30; H, 4.87; N, 3.76. Found: C, 61.35; H, 4.89; N, 3.80.

Example 2 Synthesis of 1-bromo N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (2b) and 1,7-dibromo-N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (1,7-3b)

Bromination of N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetra carboxylic diimide (1b). A mixture of 1b (2 g, 3.77 mmol) and bromine (31.1 g, 0.194 mol) in 100 ml of dichloromethane was stirred at 22-24° C. in a closed round bottom flask for 4 days. The excess of bromine was removed by air bubbling and the solvent was removed under vacuum. The crude product was purified by silica gel column chromatography with chloroform as an eluent. The first band was collected to afford dibromo perylene diimide (red solid, 650 mg, 25%) as a mixture of regioisomers (1,7-3b:1,6-3b=5:1). The second band yielded 1-bromo N,N′-Bis(ethyl propyl) perylene diimide 2b (1.15 g, 50%) as a red solid. The third band gave the unreacted perylene diimide (500 mg, 25%). The regioisomeric dibromoperylene diimides 1,7-3b and 1,6-3b could not be separated by column chromatography.

Regioisomerically pure 1,7-dibromo perylene diimide (1,7-3b) was obtained by repetitive crystallization. The mixture (200 mg) of 1,7-3b and 1,6-3b (5:1) was crystallized from 50 ml of CH₂Cl₂:Hexane (v/v, 1:1) mixture at room temperature for 5 days. The crystallization was repeated at the same conditions for two more times to yield 80 mg (40%) of pure 1,7-3b as a red solid.

1-bromo N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (2b). ¹H NMR: δ 9.78 (d, 1H, J=8.5 Hz), 8.92 (s, 1H), 8.69 (m, 3H), 8.62 (d, 1H, J=8.5 Hz), 8.61 (d, 1H, J=8.0 Hz), 5.07 (m, 2H), 2.27 (m, 4H), 1.95 (m, 4H), 0.94 (t, 6H, J=7.5 Hz), 0.93 (t, 6H, J=7.5 Hz). ¹³C {¹H} NMR (323K): δ 164.09, 163.79, 163.72, 162.89, 139.04, 133.92, 133.55, 133.48, 130.91, 130.38, 129.04, 128.84, 128.22, 128.03, 127.13, 124.03, 123.87, 123.51, 123.20, 122.75, 120.78, 58.08, 57.88, 25.04, 24.99, 11.08, 11.06. MS 608.36 [M⁺] (calcd 608.13). UV/vis (CHCl₃): λ_(max)/nm (ε/M⁻¹ cm⁻¹)=524 (61 578), 488 (40 027), 458 (15 254). Fluorescence (CHCl₃): λ_(max)=537 nm, fluorescence quantum yield Φ_(f)=0.84. Anal. Calcd. for C₃₄H₂₉BrN₂O₄: C, 67.00; H, 4.80; N, 4.60. Found: C, 66.81; H, 4.90; N, 4.53.

1,7-dibromo-N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (1,7-3b). ¹H NMR: δ 9.50 (d, 2H, J=8.0 Hz), 8.9 (s, 2H), 8.7 (d, 2H, J=8.0 Hz), 5.06 (m, 2H), 2.25 (m, 4H), 1.94 (m, 4H), 0.92 (t, 12H, J=7.5 Hz). ¹³C {¹H} NMR (323K): δ 163.66, 163.13, 138.25, 138.03, 132.96, 132.83, 130.18, 129.92, 129.48, 128.58, 128.49, 127.39, 123.71, 123.30, 120.77, 58.22, 25.15, 11.32, 11.19. MS 686.28 [M⁺] (calcd 686.04). UV/vis (CHCl₃): λ_(max)/nm (ε/M⁻¹ cm⁻¹)=526 (45 474), 490 (30 652), 458 (12 208). Fluorescence (CHCl₃): λ_(max)=545 nm, fluorescence quantum yield Φ_(f)=0.81. Anal. Calcd. for C₃₄H₂₈Br₂N₂O₄: C, 59.32; H, 4.10; N, 4.07. Found: C, 59.23; H, 4.16; N, 4.03.

Example 3 Synthesis of dibromo-perylene-3,4:9,10-tetracarboxylic diimide derivatives

A mixture of N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (1a) (50 mg, 0.085 mmol) and bromine (0.935 g, 5.8 mmol) in 3 ml of dichloromethane was heated to 50° C. in a closed vial (equipped with a Teflon liner) for 1 day. The excess of bromine was removed by air bubbling and the solvent was removed under vacuum. Silica gel column chromatography using chloroform as an eluent afforded 3a (1,7-3a:1,6-3a=3:1) as an orange solid (58 mg, 92%).

A mixture of N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetra carboxylic diimide (1b) (50 mg, 0.094 mmol) and bromine (0.935 g, 5.8 mmol) in 3 ml of dichloromethane was heated to 50° C. in a closed vial (equipped with a Teflon liner) for 2 days. The excess of bromine was removed by air bubbling and the solvent was removed under vacuum. Silica gel column chromatography using chloroform as an eluent afforded 3b (1,7-3b: 1,6-3b=3:1) as a red solid (57 mg, 89%).

A mixture of perylene-diimide, N,N′-Bis(cyclohexyl)perylene-3,4:9,10-tetracarboxylic diimide (1c) (50 mg, 0.09 mmol) and bromine (0.935 g, 5.8 mmol) in 3 ml of dichloromethane was heated to 50° C. in a closed vial (equipped with a Teflon liner) for 4 days. The excess of bromine was removed by air bubbling and the solvent was removed under vacuum. Silica gel column chromatography using chloroform as an eluent afforded 3c (1,7-3c: 1,6-3c=4:1) as a red solid (55 mg, 85%).

Example 4 Synthesis of piperidinyl-N,N′-Bis(2,4-dimethyl-pent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (5)

Compound 1-bromo N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (2a) (100 mg, 0.15 mmol) was prepared according to Example 1, and was dissolved in 10 ml of piperidine. The solution was heated to 60° C. under dry nitrogen for 5 h with stifling. Excess of piperidine was removed under vacuum and the residue was subjected to column chromatography on silica gel using chloroform as an eluent to afford 5 (96 mg, 96%) as a green solid. ¹H NMR: δ 9.87 (m, 1H), 8.63 (m, 6H), 4.77 (m, 2H), 3.52 (d, 2H, J=11.5 Hz), 2.97 (t, 2H, J=11.0 Hz), 2.72 (m, 4H), 1.90 (m, 6H), 1.12 (two doublets merged, 12H, J=6.5 Hz), 0.95 (two doublets merged, 12H, J=6.5 Hz). ¹³C {¹H} NMR: δ 165.54, 165.43, 165.34, 165.17, 164.43, 164.33, 164.21, 164.09, 152.69, 152.86, 152.83, 136.02, 136.00, 135.95, 135.93, 134.87, 134.85, 134.81, 134.79, 134.06, 134.03, 134.01, 133.98, 131.96, 131.52, 131.21, 130.79, 129.36, 129.16, 129.04, 129.02, 128.45, 127.07, 126.10, 126.08, 125.38, 125.36, 125.28, 124.72, 123.97, 123.94, 123.69, 123.67, 123.35, 123.32, 123.26, 123.24, 122.93, 122.91, 122.77, 122.76, 122.69, 122.67, 122.65, 122.63, 122.31, 122.29, 121.72, 121.69, 121.54, 121.51, 121.08, 121.05, 65.22, 65.04, 64.95, 64.89, 5298, 29.67, 29.14, 29.09, 25.84, 23.72, 21.87, 21.84, 21.77, 20.68, 20.66, 20.61, 20.60. MS 669.71 [M⁺] (calcd 669.36). UV/vis (CHCl₃): λ_(max)/nm (ε/M⁻¹ cm⁻¹)=602 (18 481), 447 (14 425). Fluorescence (CHCl₃): λ_(max)=727 nm, fluorescence quantum yield Φ_(f)=0.2. Anal. Calcd. for C₄₃H₄₇N₃O₄: C, 77.10; H, 7.07; N, 6.27. Found: C, 77.11; H, 7.11; N, 6.08.

Example 5 Synthesis of piperidinyl-N,N′-Bis(2,4-dimethyl-pent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (6)

Compound 1-bromo N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (2b) (100 mg, 0.164 mmol) was prepared according to example 2 hereinabove, and was reacted with piperidine following the procedure analogous to the synthesis of 5 as described in Example 4 hereinabove, to afford 6 (97 mg, 96%) as a green solid. ¹H NMR (400 MHz, CDCl₃, TMS): δ 9.86 (d, 1H, J=8.4 Hz), 8.60 (m, 6H), 5.10 (m, 2H), 3.50 (m, 2H), 2.97 (m, 2H), 2.30 (m, 4H), 1.82-2.0 (m, 10H), 0.95 (two triplets merged, 12H, J=7.5 Hz). ¹³C NMR (100 MHz, 323K): δ 164.39, 164.31, 164.18, 164.12, 152.74, 135.81, 134.77, 134.05, 131.37, 131.09, 130.96, 130.72, 130.66, 129.45, 129.14, 128.73, 128.44, 127.16, 125.76, 125.47, 124.91, 124.87, 123.92, 123.57, 123.42, 123.28, 123.20, 122.95, 121.73, 121.50, 121.30, 121.23, 57.79, 57.60, 53.01, 29.53, 25.87, 25.08, 23.72, 11.21, 11.07. MS 613.63 (calcd 613.29). UV/vis (CHCl₃): λ_(max)/nm (ε/M⁻¹ cm⁻¹)=601 (18 009), 447 (14 076). Fluorescence (CHCl₃): λ_(max)=726 nm, fluorescence quantum yield Φ_(f)=0.19. Anal. Calcd. for C₃₉H₃₉N₃O₄: C, 76.32; H, 6.40; N, 6.85. Found: C, 76.43; H, 6.52; N, 6.59.

Example 6 Synthesis of trimethylsilylacetylene-N,N′-Bis(2,4-dimethylpent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (7)

N,N′-Bis(2,4-dimethylpent-3-yl) perylene-3,4:9,10-tetracarboxylic diimide (2a) was prepared according to Example 1 hereinabove. In a glove box filled with dry nitrogen 2a (100 mg, 0.15 mmol), Pd(PPh₃)₄ (17 mg, 0.015 mmol), trimethylsilyl acetylene (22 mg, 0.22 mmol), and 2 ml of diisopropyl amine were mixed in a vial equipped with a magnetic stirrer, then CuI (1.5 mg, 0.008 mmol) was added to the mixture. The mixture was allowed to stirr at room temperature overnight. The solvent was removed under vacuum and resulting mixture was subjected to silica gel chromatography using chloroform as an eluent to yield 98 mg (96%) of 7 as a red solid. ¹H NMR: δ 10.42 (two doublets, 2H, J=8.5 Hz), 8.82 (s, 1H), 8.80 (s, 1H), 8.40 (m, 10H), 4.78 (m, 4H), 2.77 (m, 8H), 1.14 (two doublets merged, 24H, J=6.5 Hz), 0.96 (two doublets merged, 24H, J=6.5 Hz), 0.42 (s, 9H). ¹³C {¹H} NMR: δ 165.28, 165.08, 164.59, 164.16, 164.00, 163.97, 163.47, 139.35, 138.73, 134.68, 134.59, 134.54, 134.52, 134.33, 134.32, 134.30, 134.28, 133.96, 133.94, 133.90, 133.87, 131.81, 131.53, 131.46, 131.09, 130.80, 130.76, 129.08, 129.07, 128.63, 128.61, 127.23, 127.19, 127.15, 126.67, 124.04, 124.02, 123.83, 123.80, 123.50, 123.45, 123.43, 123.41, 123.21, 123.18, 123.05, 123.03, 123.01, 122.99, 122.88, 122.85, 122.55, 122.54, 121.98, 121.96, 119.96, 119.93, 119.90, 107.21, 107.15, 107.09, 105.91, 65.27, 65.25, 65.19, 65.18, 29.12, 29.10, 29.05, 29.02, 21.80, 21.76, 21.72, 20.58, 20.56, 20.51, 20.49, −0.40. MS 682.47 [M⁺] (calcd 682.32). UV/vis (CHCl₃): λ_(max)/nm (ε/M⁻¹ cm⁻¹)=537 (66 690), 499 (39 606), 467 (14 050). Fluorescence (CHCl₃): λ_(max)=547 nm, fluorescence quantum yield Φ_(f)=0.76. Anal. Calcd. for C₄₃H₄₆N₂O₄Si: C, 75.63; H, 6.79; N, 4.10. Found: C, 75.99; H, 6.98; N, 3.82.

Example 7 Synthesis of trimethylsilylacetylene-N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (8)

Compound 8 was obtained as a red solid in 97% yield using procedure analogous to the one used for the synthesis of 7. ¹H NMR: δ 10.15 (d, 1H, J=8.0 Hz), 8.32-8.63 (m, 6H), 5.06 (m, 2H), 2.27 (m, 4H), 1.98 (m, 4H), 0.98 (m, 12H), 0.45 (s, 9H). ¹³C NMR (323K): δ 164.33, 164.12, 163.62, 138.94, 134.79, 134.74, 134.43, 134.08, 131.30, 131.01, 130.92, 129.37, 128.91, 127.46, 127.39, 127.35, 126.98, 124.22, 124.00, 123.63, 123.43, 122.97, 122.72, 120.17, 107.33, 106.28, 58.16, 58.07, 25.29, 25.23, 11.30, 11.26, −0.34. MS 626.70 [M⁺] (calcd 626.26) (UV/vis (CHCl₃): λ_(max)/nm (ε/M⁻¹ cm⁻¹)=537 (60 348), 499 (35 877), 467 (12 743), 433 (5 562). Fluorescence (CHCl₃): λ_(max)=546 nm, fluorescence quantum yield Φ_(f)=0.76. Anal. Calcd. for C₃₉H₃₈N₂O₄Si: C, 74.73; H, 6.11; N, 4.47. Found: C, 74.45; H, 6.27; N, 4.10.

Example 8 Synthesis of 1-piperazinyl N,N′-Bis(2,4-dimethyl-pent-3-yl) perylene-3,4:9,10-tetracarboxylic diimide (9)

Piperazine (1 g, 11.6 mol) in 15 ml of toluene was taken in a round bottom flask and immersed into oil bath at 60° C. with stifling for 30 min. Then 1-bromo-N,N′-Bis(2,4-dimethyl-pent-3-yl)perylene diimide (2a) (400 mg, 0.6 mmol) and 400 mg (2.9 mmol) of anhydrous potassium carbonate were added into the reaction mixture. The reaction was continued for 10 h. After removing the toluene by vacuum evaporation, the remaining residue was taken in dichloromethane and extracted with distilled water. The organic layer was separated and dried over anhydrous Na₂SO₄. The solvent was removed under vacuum and the mixture was subjected to silica gel column chromatography. The first band, unreacted starting material, was collected by chloroform elution and then green colour product was collected by to chloroform:methanol (9:1) mixture to yield 220 mg (54%) the mono piperazine derivative as a dark-green solid. ¹HNMR (500 NMR, CDCl₃, TMS): δ 10.00 (two doublets merged, 1H, J=8 Hz), 8.5-8.7 (m, 6H), 4.75 (m, 2H), 3.52 (m, 2H), 3.0-3.2 (m, 5H), 2.63-2.75 (m, 6H), 1.12 (two doublets merged, 12H, J=6.5 Hz), 0.93 (two doublets merged, 12H, J=6.5 Hz). ¹³C NMR (500 NMR, CDCl₃, TMS): δ 165.49, 165.37, 165.24, 165.19, 164.38, 164.27, 164.11, 151.90, 135.75, 135.72, 135.68, 135.66, 134.80, 134.77, 134.74, 134.72, 134.11, 134.09, 134.06, 131.91, 131.62, 131.16, 130.90, 129.43, 129.33, 129.02, 128.73, 127.12, 125.53, 125.49, 125.14, 124.82, 124.10, 124.08, 123.81, 123.49, 123.47, 123.32, 123.30, 123.13, 123.09, 123.04, 122.71, 122.69, 122.43, 122.41, 121.95, 121.92, 121.76, 121.32, 121.29, 65.26, 65.09, 65.00, 64.96, 51.44, 51.28, 29.14, 29.10, 21.88, 21.79, 20.67, 20.61. MS 671.94 [M+1] (calcd 671.36). UV/vis (CHCl₃): λ_(max)/nm (ε/L mol⁻¹ cm⁻¹)=588 (18 629), 446 (12 163). Fluorescence (CHCl₃): λ_(max)=705 nm, fluorescence quantum yield Φ_(f)=0.3. Anal. Calcd for C₄₂H₄₆N₄O₄:

Example 9 Synthesis of 1-piperazinyl N,N′-Bis(ethyl propyl)perylene-3,4:9,10-tetracarboxylic diimide (10)

Piperazine (1 g, 11.6 mol) in 15 ml of toluene was taken in 50 ml round bottom flask under nitrogen and immersed into oil bath at 60° C. with stirring for 30 min 1-bromo-N,N′-Bis(ethyl propyl) perylene diimide (2b) (100 mg, 0.188 mmol) was added and reaction was for 2 days. After removing the toluene by vacuum, the remaining residue was taken in dichloromethane (100 ml) and extracted with distilled water (2×100 ml). The organic layer was separated and dried over anhydrous Na₂SO₄. The solvent was removed under vacuum and the mixture was subjected to silica gel column chromatography. The first band, unreacted starting material was collected by chloroform elution and then green colour product was collected by chloroform:methanol (9.5:0.5) mixture to yield 70 mg (60%) the mono piperazine derivative. ¹HNMR (400 NMR, CDCl₃, TMS): δ 10.00 (d, 1H, J=7 Hz), 8.54-8.67 (m, 6H), 5.1 (m, 2H), 3.47 (d, 2H, J=12 Hz), 3.23 (t, 2H, J=10 Hz), 3.15 (d, 2H, J=12 Hz), 3.06 (t, 2H, J=10 Hz), 2.29 (m, 4H), 1.96 (m, 4H), 0.94 (t, 12H, J=7.2 Hz). ¹³C NMR (400 NMR, CDCl₃, TMS): δ 164.33, 164.23, 164.08, 152.07, 135.25, 131.04, 129.42, 129.13, 127.18, 125.66, 125.24, 125.20, 125.05, 124.06, 123.63, 123.53, 123.42, 123.32, 123.23, 123.04, 122.00, 121.66, 121.60, 121.48, 57.83, 57.63, 52.71, 45.85, 25.06, 11.18, 11.12. MS 615.82 [M+1] (calcd [M] 614.73). UV/vis (CHCl₃): λ_(max)/nm (ε/L mol⁻¹ cm⁻¹)=585 (22 419), 446 (15 567). Fluorescence (CHCl₃): λ_(max)=712 nm, fluorescence quantum yield Φ_(f)=0.23.

Example 10 Synthesis of 4-amino phenyl acetylene N,N′-Bis(ethyl propyl)perylene-3,4:9,10-tetracarboxylic diimide (11)

Sonogashira coupling. 100 mg of Monobrominated PDI-2b, 5 mol % of Pd(PPh₃)₄, 1 eq. of 4-ethenyl aniline were taken in a vial with magnetic stirrer, then 2 ml of diisopropyl amine was added followed by 5 mol % of CuI. The mixture was allowed to stir at room temperature overnight. The TLC showed the formation of product with dark brown colour. The product was purified by silica gel chromatography using chloroform as an eluent. The yield is quantitative.

The ¹HNMR (400 NMR, CDCl₃, TMS) of compound of formula 11 is depicted in FIG. 9.

Example 11 Synthesis of 4-amino phenyl acetylene N,N′-Bis(2,4-dimethyl-pent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (12)

Sonogashira coupling. 100 mg of 2a, 5 mol % of Pd(PPh₃)₄, 1 eq. of 4-ethenyl aniline were taken in a vial with magnetic stirrer, then 2 ml of diisopropyl amine was added followed by 5 mol % of CuI. The mixture was allowed to stir at room temperature overnight. The TLC showed the formation of product with dark brown colour. The product was purified by silica gel chromatography using chloroform as an eluent. The yield is quantitative.

The ¹HNMR (400 NMR, CDCl₃, TMS) of compound of formula 12 is depicted in FIG. 10.

Example 12 Synthesis of N-isonicotinoyl 1-piperazinyl N,N′-Bis(2,4-dimethyl-pent-3-yl)perylene-3,4:9,10-tetracarboxylic diimide (13) name.

Mixture of equivalent amounts in dichloromethane. The residue after removing solvent was subjected to silica gel column chromatography first using dichloromethane as an eluent and then with 2% of ethanol in dichloromethane. Purple colour band was collected. The ¹H NMR showed the formation of desired product.

The ¹H NMR (400 NMR, CDCl₃, TMS) of compound of formula 13 is depicted in FIG. 11.

Example 13 Synthesis of 4-ethynyl phenyl acetylene N,N′-Bis(ethyl propyl) perylene-3,4:9,10-tetracarboxylic diimide (14)

Sonogashira coupling (analogous to Example 11). The reaction was stopped after 3 h to prevent the formation of self coupling between alkynes. CuI can be replaced with ZnBr₂.

The ¹HNMR (400 NMR, CDCl₃, TMS) of compound of formula 14 is depicted in FIG. 12.

Example 14 Synthesis of 1-ethynyl N,N′-Bis(ethyl propyl)perylene-3,4:9,10-tetracarboxylic diimide (15)

Starting material 5b (50 mg) in dichloromethane (10 ml) and KF (20 mg) mixed in MeOH (3 ml). It was allowed to stir at RT for 2 days to get complete deprotection. Care should be taken while adding MeOH in such a way that PDI derivative does not precipitate. After workup with water to remove KF and evaporation of solvent, the mixture was subjected for column chromatography using chloroform as an eluent to yield the product (80%).

Example 15 Synthesis of Compound of (2,2′-bipyridine)-5-N,N′-Bis(ethyl propyl) perylene-3,4:9,10-tetracarboxylic diimide (16)

Reflux in toluene (in a closed vial—taken inside clove box) for two days. Product (yield 20%) was separated through preparative TLC using dichloromethane as an eluent.

The ¹HNMR (400 NMR, CDCl₃, TMS) of compound of formula 16 is depicted in FIG. 13.

Example 16 Synthesis of 1-(N,N′-Bis(ethyl propyl)perylene-3,4:9,10-tetracarboxylic diimide) 4-acetylene phenyl ethynyl)-7-piperidinyl N,N′-Bis(ethyl propyl)perylene-3,4:9,10-tetracarboxylic diimide (17)

Compound of formula 17 was prepared using sonogashira coupling procedure used in the above examples. Compound of formula 17 was purified through silica gel column chromatography using chloroform as eluent.

The ¹HNMR (400 NMR, CDCl₃, TMS) of compound of formula 17 is depicted in FIG. 14.

Example 17 Photophysical and Redox Properties of Compounds 2-8

Photophysical and redox properties of monobrominated PDI derivatives 2a,b are similar to those of dibrominated 3a,b. The latter are very similar to the reported photophysical and redox characteristics of 1,7-dibromo-PDIs. Monopiperidine PDI derivatives 5 and 6 show absorption and emission that is less red-shifted than the one observed for disubstituted piperidine derivatives (absorption maximum at 680 nm, emission at 770 nm) as expected for lower electron-donating ability of one piperidine group vs. two such groups. The emission quantum yields (0.2) are identical for compounds 5 and 6 and 1,7-dipiperidine PDI derivative.

TABLE 1 Absorption and emission properties of compounds 2-8 in chloroform, and redox potentials in dichloromethane (in V vs SCE)^(a) absorption emission λ_(max) ^(b) λ_(em) ^(b) Compound (ε)^(c) (λ_(ex))^(b) Φ ¹E_(1/2) ^(RED) ²E_(1/2) ^(RED) E_(1/2) ^(OX) 2a 524 (74669) 538 (488) 0.92 −0.59 −0.80 2b 524 (61578) 537 (488) 0.88 −0.59 −0.79 1,7-3a 526 (49825) 545 (490) 0.82 −0.52 −0.73 1,7-3b 526 (45474) 545 (490) 0.81 −0.54 −0.76 5 602 (18481) 727 (600) 0.20 −0.66 −0.86 1.06 6 601 (18009) 726 (600) 0.19 −0.74 −0.93 1.06 7 537 (66690) 547 (493) 0.76 −0.61 −0.81 8 537 (60348) 546 (493) 0.76 −0.60 −0.80 ^(a)All measurements were performed at room temperature; ^(b)in nm; ^(c)in M⁻¹ cm⁻¹.

Example 18 X-Ray Analysis of 1,7-dibromo-N,N′-Bis(ethylpropyl)perylene-3,4:9,10-tetracarboxylic diimide (1,7-3b)

The structure of 1,7-3b was further elucidated by X-ray crystallography. Single crystals of 1,7-3b suitable for X-ray analysis were grown from dichloromethane/hexane solution. The central six-membered ring was twisted (FIG. 5) with dihedral angles of 23.3° and 21° associated with bay area carbon atoms C1-C22-C34-C12 and C6-C23-C33-C7 respectively, these values being similar the core twist angle of 24° in N,N′-dicyclohexyl-1,7-dibromo PDI.

Example 19 Computational Methods

All calculations were carried out using Density Functional Theory (DFT) as implemented in Gaussian 03 program (Frisch, M. J.; Trucks, G. W. et al; Gaussian, Inc., Wallingford Conn. 2004. Geometry optimizations for minima were carried out using the standard Schlegel algorithm (Peng, C.; Ayala, P. Y.; Schlegel, H. B.; Frisch, M. J. J. Comput. Chem. 1996, 17, 49. or Schlegel, H. B. J. Comput. Chem. 1982, 3, 214) in redundant internal coordinates until in the neighborhood of the solution, and then continued using analytical second derivatives. Optimizations for transition states were carried out with an initial guess for the transition state being generated from manual manipulation of the geometry using MOLDEN (Schaftenaar, G.; Noordik, J. H. J. Comput.-Aided Mol. Design. 2000, 14, 123-129). Geometries were optimized using the default pruned (75,302) grid, or when necessary for conversion with the “ultrafine” grid, i.e., a pruned (99,590) grid.

The B3LYP exchange correlation functional (three-parameter hybrid density functional method) (Becke, A. D. J. Chem. Phys. 1993, 98, 5648-5652. Stevens, P. J.; and Devlin, F. J.; Chabalowski, C. F.; Frisch, M. J. J. Phys. Chem. 1994, 98, 11623) was employed together with two basis sets. The first, D95V, is the Huzinaga-Dunning double-ζ basis set (Dunning Jr., T. H.; Hay, P. J. Modern Theoretical Chemistry; Plenum: New York, 1976; Vol. 3) and the second, cc-pVDZ, is the Dunning correlation-consistent polarized valence double-basis set (Dunning Jr., T. H. J. Chem. Phys. 1989, 90, 1007-1023). Geometry optimizations were carried out using the former basis set while the energetics of the reaction were calculated at these geometries with the latter basis set, to increase the accuracy of the results. Zero-point and RRHO (rigid rotor-harmonic oscillator) thermal corrections were obtained from the unscaled computed frequencies.

Results

DFT calculations at the B3LYP/cc-pVDZ//B3LYP/D95V level of theory were performed for the following PDI derivatives:

For each compound two isomers were located: exo, where the N—CHR₂ hydrogen atoms are pointing to the opposite directions and endo, where they point to the same direction as depicted in FIG. 7. For each isomer couple the transition state for the rotation around the N—C(sp³) bond was located (FIG. 7). The rotation barriers around the N—CHR₂ bonds corresponded well to the steric bulk of the imide substituents: 12.7 kcal/mol for 2R=Cy, 17.0 kcal/mol for R=Et, and 31.6 kcal/mol for R═^(i)Pr. These findings showed that the rotation around the N—C bond for 2R=Cy and R=Et can occur at room temperature, while the rotation around the N—C bond for R═^(i)Pr was restricted due to larger steric bulk of dimethylpenthyl group. The rotation around the N—C bond for R=Et (rotation time of ca. 300 msec as estimated from the kinetic barrier) was comparable to the NMR time scale, which is in agreement with slight broadening of the ¹H and ¹³C NMR signals of 2b-6. The rotational barriers of the brominated PDI derivatives were similar to the nonbrominated molecules. Thus, for monobrominated PDI with R═^(i)Pr, the N—C rotation barrier was found to be 32.8 kcal/mol, and for the 1,7-dibrominated PDI with R═^(i)Pr the barrier for rotation is 32.5 kcal/mol.

The motion associated with the PDI core twist, was addressed and the PDI-Br-2a (where R═^(i)Pr) (FIG. 8A) was analyzed. The PDI skeleton was twisted, for the congested bay region. The barrier for the PDI aromatic core twisting (FIG. 8A) was found to be rather low, 2 kcal/mol, therefore, core twist is expected to be facile. Accordingly, no additional isomers were expected to be observed as a result of PDI bromination. Similar results were obtained for the PDI derivative with two Br atoms (compound 3a). Core twist barrier for this case was found to require a slightly higher energy of 6 kcal/mol (FIG. 8B).

Example 21 Synthesis of Compound (18)

The coupling reaction was carried out in the glove box under N₂ atmosphere.

Inside the glove box, 130 mg of PDI-Br (1 eq, Mw=665.62 gr/mole, n=1.95×10⁻⁴ mole) were weighed in a clean vial. 14.65 mg of Pd₂(DBA)₃, (0.05 eq) (10% mole, Mw=915.72 gr/mole, n=1.6×10⁻⁵ mole) & 10% mole of tri-(t-Butyl)phosphine (6.75 mg, Mw=211.3902 gr/mole) were added to PDI-Br dissolved in 10 ml of toluene. The mixture was stirred for 5 min & then added dropwise to a toluenic solution of Terpy-acetylene-tributylTin. According to the TLC, the reaction is completed in 2 h. Silica gel column chromatography resulted in 231 mg (Mw=918.09 gr/mole) of the product, Terpy-PDI(dmp), 84% yield. Mass-spectra and NMR confirm that the product was obtained as presented in FIG. 15.

Example 21 Synthesis of Compound (19)

The coupling reaction was carried out in the glove box under N₂ atmosphere.

To a stirred solution of 30 mg (45 μmol) of monobromo-PDI in toluene (1 mL) was added a solution of 0.886 mg (2.25 μmol) Allylpalladium-chloride-dimer and 0.910 mg (4.5 μmol) P(^(t)Bu)₃ in 145 μL THF. Subsequently, diisopropylamine (0.75 μL) was added, followed by the dropwise addition of a solution of 3 mg (15 μmol) 5,5′-DiEthynyl-2,2′-Bipyridine in toluene (0.5 mL). The dark-red solution was stirred overnight. During that time, the solution became darker and a dark-red solid precipitated. After the reaction was finished (checked by TLC) the solvent was evaporated in high vacuum and the product purified using silica column chromatography (eluent: CHCl₃/MeOH (MeOH gradient 1%-2%), silica 40-63 μm). For further purification, all solvents were evaporated from the product fraction; the resulting solid was dissolved in a minimum amount of CHCl₃, precipitated in acetone and centrifuged. The precipitate was washed 4× with acetone and dried in the vacuum.

Yield: 11 mg (8 μmol, 53% with respect to 5,5′-DiEthynyl-2,2′-Bipyridine used). Mass-spectra are consistent with the structure. The product was characterized by NMR as presented in FIG. 16.

While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. 

1. A process for the preparation of dibrominated perylene diimide compound represented by the structures of formula 1,6-3 and 1,7-3;

wherein R₁ and R₂ are the same or different substituted or unsubstituted linear or branched alkyl group, substituted or unsubstituted saturated carbocyclic or heterocyclic ring or aryl; comprising the steps of a) brominating compound of formula 1

wherein R₁ and R₂ are as defined above; in the presence of bromine and a chlorinated solvent at reflux for a period of time sufficient to obtain a mixture comprising compounds of formula 1,6-3 and 1,7-3; and b) separating between 1,6-3 and 1,7-3 regioisomer compounds by recrystallizing compound of formula 1,7-3 yielding crystalline pure perylenediimide of formula 1,7-3, thereby separating between said regioisomer compounds.
 2. The process of claim 1, wherein R₁ and R₂ are the same or different dimethylpentyl, tertbutyl, ethylpropyl, linear alkyl (C₁-C₁₂), or cyclohexane.
 3. The process of claim 1, wherein said chlorinated solvent is dichloromethane, chloroform, or chlorinated aliphatic solvent.
 4. The process of claim 1, wherein said period of time is between 1-4 days.
 5. The process of claim 1, wherein said period of time is between 24-48 h.
 6. The process of claim 1, wherein said recrystallization is from dichloromethane/hexane mixture (v/v, 1:1).
 7. A process for the preparation of dibrominated perylene-diimide and monobrominated perylene-diimide compounds represented by the structures of formula 2, 1,6-3 and 1,7-3;

wherein R₁ and R₂ are the same or different substituted or unsubstituted linear or branched alkyl group, substituted or unsubstituted saturated carbocyclic or heterocyclic ring or aryl; comprising the steps of a) brominating compound of formula 1

wherein R₁ and R₂ are as defined above; in the presence of bromine and a chlorinated solvent at a temperature range of between about 15-30° C. for a period of time sufficient to obtain a mixture comprising compound of formula 2, 1,6-3 and 1,7-3; b) isolating compound of formula 2 by chromatography; and c) separating between 1,6-3 and 1,7-3 regioisomer compounds by recrystallizing compound of formula 1,7-3 yielding crystalline pure perylene-diimide of formula 1,7-3, thereby separating between said two regioisomer compounds.
 8. The process of claim 7, wherein R₁ and R₂ are the same or different dimethylpentyl, tertbutyl, ethylpropyl, linear alkyl (C₁-C₁₂), or cyclohexane.
 9. The process of claim 7, wherein said chlorinated solvent is dichloromethane, chloroform, or chlorinated aliphatic solvent.
 10. The process of claim 7, wherein said period of time is between 1-4 days.
 11. The process of claim 10, wherein said period of time is between 3-4 days.
 12. The process of claim 7, wherein said temperature range is between 22-24° C. 